1. Field of the Invention
The present invention relates to a printing apparatus, such as electrophotographic printer, having plural image forming section.
2. Description of Related Art
A printing apparatus, such as electrophotographic printer, has an image processing section and an image forming section. In the image processing section, image information received from a host device, is transformed to image data. In the image forming section, photosensitive drum is charged negative with a charging roller. And, a electrostatic latent image of the image data mentioned above, is formed with LED head, on the photosensitive drum. On this electrostatic latent image, a toner image is formed with using a developing roller, a toner conveying roller, a developing blade etc. In this process, toner remained on the photosensitive drum, is removed with a cleaning equipment.
Moreover, in a printing apparatus, such as color electrophotographic printer, has above image forming apparatus of four, corresponding to each color of Y, M, C, K. These four image forming sections are installed at prescribed positions in the printing apparatus. To each of these four image forming sections, each image data of prescribed color is sent from the image processing section. Each of four image forming sections reproduces each image on a print sheet, based on each image data. In this way, a color image is reproduced. In this kind of conventional printing apparatus such as color electrophotographic printer, a technique for reproducing monochromic image effectively, is disclosed in public (c.f. JP2001-183886).
However, in the conventional technique, it is necessary for the printing apparatus to attach all of four image forming sections as each color of Y, M, C, K, at each prescribed position in the printing apparatus, even when, for example, a monochromic image is reproduced. Moreover, the prescribed position is limited fixedly beforehand. And, to change the position is difficult. Therefore, it is difficult to realize monochromic printing apparatus enabling continuous printing for a long time, or printing apparatus enabling continuous printing for a long time with only two colors.